Transmission / Overdrive: What would cause a failure of the needle bearings in the cluster gear?

[Ted Preston]

So I pulled up to a stop sign recently, and the car acted like it was frozen in neutral. It would not go into first, nor into reverse. I tried a few more times, and it finally engaged first gear. I limped the one mile home, with a knock that sounded like a rod bearing. Later I fired it up when I had time to diagnose, and it drove just fine, like nothing was wrong. Then it did the same thing again.


To make a long story short, I disassembled the transmisson last night, and found broken up bits of needle bearing scattered everywhere in the main tranny case. Upon further disassembly, I determined that they were the needle bearings that normally reside inside the cluster gear.

I've now ordered all the numerous parts that will require replacement. Before I re-assemble, I'm thinking about the future, and wondering why those bearings would have disintegrated in the first place. Because they live inside the cluster shaft, and are bathed constantly in oil, it seems like they would last pretty much forever, but these obviously did not. They actually wore through the thrust washers and worked their way out of the cluster gear/shaft assembly into the rest of the tranny.

Any thoughts? (yeah, I know: "pics or it didn't happen." You guys know I'm normally good for some carnage pics: http://forum.studebakerdriversclub.c...hlight=carnage )

[Flashback]

I don't know what trans you have, but there are several things that could happen here. Has it been built lately? The center spacer (in the picture below) could have been the problem. There are also small spacers on the ends to keep the bearings straight. The cluster could be worn. the shaft needs to be checked for wear. If it was built and one needle was left out, that could be a problem. Thrust washers on the ends (cluster to case) need to be checked. If it was run dry before, that might be the cause. You may already know everything I have said. Be sure you have some sort of manual to check assembly and specs. Here's a shot of a T-86 with the spacer and shaft to the left. OBTW, was the right lube used?

[Ted Preston]

Flashback, my tranny is a T96, which for practical purposes is identical to your T86, though I've read that the T86 is sturdier. They sure look identical from your photo.

I don't know whether the transmission was ever rebuilt, nor what lubricant may have been used through the years. I can tell you that the lubricant was awfully black and looked well used up, though the level was fine. No indication that the tranny had been rebuilt recently. It was covered in crud, and the lubricant was pure black.

Here's a photo of the remains of the needle bearings and the thrust washers, which got eaten away in the centers by the bits of old bearing grinding against them. (am I right that the center hole in these thrust washers should be the same diameter as the shaft?) I'm guessing the countershaft was spinning just on the spacer. Amazingly, I got no sense of anything wrong in about three hundred miles of driving since I bought this car, except a rough clutch engagement when starting in first gear. The only more noticeable problems cropped up in the last five miles.

Seeing the holes in the center of these washers makes it obvious how the bits of needle bearing wound up rattling around inside the main case.

I have no idea how many miles may have been on this tranny, but I'm guessing lots. Oddly, the needle bearings in the input shaft look great. I will re-use them. The gears sure got chewed up, though. I'll be replacing the countershaft "cluster" gears as well as the first/reverse gear. Oddly, the input shaft gear is fine and re-useable, despite having had a chunk of needle bearing lodged between two teeth.

[PackardV8]

About the only thing which could cause that damage on a T96 is running without lubricant. Looks like it was severely overheated, then refilled with lube.

jack vines

[Noxnabaker]

Hmmm... There's a thing if the gearbox has been standing for a long time, has it? Do you know where it comes from, if it's been on a scrapyard once? ...& maby there's been water in it, if only a small amount that dried up by the heat when it started to get driven again...?
Then a checkup (in any case) of the other bearings might be a sweet thing to do, but you've probably already guessed that.

Nox.

[Ted Preston]

Hmmm... There's a thing if the gearbox has been standing for a long time, has it? Do you know where it comes from, if it's been on a scrapyard once? ...& maby there's been water in it, if only a small amount that dried up by the heat when it started to get driven again...?
Then a checkup (in any case) of the other bearings might be a sweet thing to do, but you've probably already guessed that.

Nox.

That makes sense. If a gearbox got water inside somehow, these needle bearings are in a low spot, and might get submerged in water and turn rusty. I don't know enough of this car's history to know whether that's a possibility. It would seem unlikely that water could get into a tranny if it is in place under the car, unless maybe the car got submerged in water somehow. Then water could get in relatively easily through the input shaft bearing, which has no seal besides an oil slinger.

[K-Hawk]

Would we all be better off if we flushed our transmissions every 100000 or so miles or certainly when installing a used unit, with some diesel fuel soak for a day or 2,spin with wheels in air? drain and refill with some 90 weight .

[Ted Preston]

Would we all be better off if we flushed our transmissions every 100000 or so miles or certainly when installing a used unit, with some diesel fuel soak for a day or 2,spin with wheels in air? drain and refill with some 90 weight .

It's hard to argue that the routine you suggest is a bad idea, maybe even as often as 50,000 miles. It would remove the bits of metal that act as an abrasive inside the tranny, and renew the lubricant. Nothing bad in either of those ideas, so long as you don't go out and drive the car with the diesel in the tranny.

[gordr]

Ted, the T96 looks a lot like the T86, except it's considerably smaller in all respects, and has a 4-bolt top cover instead of a 6-bolt top cover. Set the two beside one another, and the difference is obvious.

When a transmission has grenaded that badly, I'd recommend you replace it outright, or least replace all the internal parts. Fine particles of hardened steel from those needles had to have been circulating with the oil, and causing wear on the gear teeth and the other bearings. Even if you can't see it, the wear is there.

You didn't say if it was an overdrive transmission; if not the straight 3-speed T96's are quite plentiful. Me, I regard those as parts sources to fix overdrives.